The invention relates to a centrifuge drum with discharge valves for the solids settled out in the clarification or separation of liquids containing solids, in which the valves are distributed uniformly about the circumference in the plane of greatest diameter, the movable valve bodies are shielded against the pressure of the drum charge and are closed by centrifugal force during operation, and can be opened by means of a control liquid while the drum is turning at full speed.
Centrifuge drums of this kind are known, and are used chiefly for liquids which contain solids of soft, yeast-like consistency, such as for example culture filtrates for the production of antibiotics, bacterial cultures, and the like, in which the content of the solids can differ greatly.
A centrifuge drum of this kind is known, for example, from German Pat. No. 924,979. It is a disadvantage in this drum that the valves themselves and the conduits supplying the control liquid are disposed inside of the centrifuge chamber and solids chamber. By this arrangement of the valves and conduits the capacity of the solids chamber is greatly reduced, on the one hand, and on the other hand operations under sterile conditions, which are required or necessary in the case of a great number of liquids, are impossible.
Furthermore, in the event of leaks in the sealing rings, control liquid can find its way into the solids chamber or into the liquid being centrifuged, and in most cases this must be avoided.
Also, the cleaning-in-place system which has been introduced in many industries can be used with only poor success in these drums, since they contain too many places where solid particles can lodge and where they cannot be reached by the cleaning fluid.
FIG. 6 in German Pat. No. 717,992 shows a drum in which the solids chamber is largely free of valve fittings. The chief disadvantage, however, consists in the fact that the valve piston, when operated for opening, has to be moved against the pressure of the solids lodged in the solids chamber and of the liquid charge in the drum.
In many cases, the opening force which has to be produced by the control liquid--normally water--does not suffice to bring the valve piston to the opening position against the above-mentioned pressure acting in the closing sense.
Since the known drums equipped with discharge valves do not satisfy the requirements which a centrifugal separator must today fulfill, more complicated and expensive centrifugal separators are often used for the above-mentioned applications, such as, for example, centrifugal sepparators of the self-cleaning type equipped with a movable piston slide valve.
Where a plurality of centrifuges must be connected in series, as in the case of the countercurrent extraction of antibiotics, the process then becomes uneconomical.
Precisely for these and other processes, however, centrifugal separators with discharge valves are very desirable since they are substantially simpler in construction, have larger separating chamber and solids chamber capacities, and discharge the settled solids very effectively.